1 / 3 minus 15 / 2 minus 63 / 4

1 / 3 minus 15 / 2 minus 63 / 4

First, the sign before the fraction is positive and negative alternation, and then the order of molecules is 1,2,3,4,5,6 Finally, the denominators are 2 ^ 2-1,4 ^ 2-1,6 ^ 2-1,8 ^ 2-1 So the next number should be 5 / 99

Find the law - 3, - 15, - 35, - 63 what is the 100th number? What is the nth number?

The rule is - 1 * 3, - 3 * 5, - 5 * 7, - 7 * 9
The nth number is - (2n-1) * (2n + 1) = 1-4n ^ 2

Mathematical laws: 1, - 1 / 3,1 / 5, - 1 / 7,1 / 9, - 1 / 11,1 / 13, - 1 / 15 (2002), (2003)

The general term is (- 1) ^ (n-1) * 1 / (2n-1)
So: the number of 2002 is: - 1 / 4003, and the number of 2003 is 1 / 4005